Most known log roll winders cut the web while the web is in the air, rather than against a drum. As the knife cuts, it forces the web against a new core. However, as the tail of the web is not supported, the web, particularly thin webs, will not lay down smoothly against the core and wrinkles are produced on the outer wraps. Winders of this type are made by Fuji Tekko.
U.S. Pat. No. 4,775,110 to Welp et al. describes a winding system in which a complex cutting system is used to sever the web. One cutter perforates the web along a line and the web is braked to sever the web. Cutting is not performed on the fly. A hot wire can be used as another cutter and a vacuum can be used on the feed drum to secure the web.
Some continuous, high speed log roll winders which wind a continuous web of material around large rolls or drums transfer the web to a core on a wind-up spindle disposed against the drum. In one system attempted by 3M Company, the assignee of this invention, the winding is transferred from one wind-up spindle to another simply by moving the wind-up spindles against and away from the rotating drum. However, as the web which typically travels at speeds of 120 m/min (although the speed can vary), it requires precise timing. When transferring from the first wind-up spindle to the second wind-up spindle, the first wind-up spindle must be lifted off of the rotating drum before the cut end arrives. In doing this, the last portion of the web wrapped on the first wind-up spindle is uncontrolled and must be prevented from wrinkling. When transferring from the second to the first wind-up spindle, the first wind-up spindle must be moved against the rotating drum before the cut end arrives. Then the web is peeled off of its core on the second wind-up spindle while being prevented from wrinkling.
A roll winder made by Stahlkontor Maschinenbau GmbH winds a web at only one wind-up location. The web, drum, and wind-up roll stop for the web to be cut before the drum. Following the cut, the drum and roll of web resume turning to wind up the tail of the web while the incoming web remains stopped. Next, the roll of web is unloaded, and an empty core is loaded in its place. Finally, the winder begins winding on the new core. Thus, this winder does not cut and transfer web on the fly. If the winder is used to wind on line at the end of a continuous web maker, an accumulator is required to absorb incoming web during the cut and transfer, and web speeds are limited to 70 m/min to prevent tension problems. Additionally, the Stahlkontor machine cuts the web before it contacts the drum, leaving the web prone to wrinkling.
In the rewinder of U.S. Pat. No. 4,487,377 to Perini, after the web is cut, the leading edge of the web is permitted to fly rearwardly off of the main winding drum. This folded back portion is subsequently adhered to a core to begin winding another roll. No function for folding back the beginning portion of the web is disclosed.